388 ARACHNIDA—ARANEAE CHAP. 
terricolous, but inhabit trees, either boring holes in the bark, 
or constructing a sort of silken retreat fortified by particles 
of wood. 
(iv.) The CTENIZINAE form a large group, including some 
forty genera. All the “ Trap-door ” Spiders of the Continent fall 
under this sub-family, which, moreover, has representatives in all 
the tropical and sub-tropical regions of the world. <A rastellus is 
always present, and the eyes form a compact group on an emin- 
ence. The coxae of the pedipalps are longer than in the groups 
previously mentioned, and there is no production of the internal 
angle. The labium is generally free. 
The commonest European genus is Nemesia, of which about 
thirty species inhabit the Mediterranean region. The cephalo- 
thorax is rather flat, and the central fovea is recurved (-—). 
The burrow is sometimes simple and sometimes branched, and 
the trap-door may be either thin, or thick with bevelled edges. 
Allied genera are Hermacha and Rachias in South America, 
Spiroctenus in South Africa, Genysa in Madagascar, Scalidognathus 
in Ceylon, and Arbanitis in New Zealand. The genus Cteniza 
(fovea procurved ~~) possesses only a single species (C. sawvaget), 
found in South-East France and Italy. 
Pachylomerus is a widely-distributed genus, being represented 
in North and South America, Japan, and North Africa. The 
tibiae of the third pair of legs are marked above by a deep 
impression near the base. A closely allied genus, Conothele, 
inhabits Southern Asia and New Guinea. 
The widely-distributed genus <Acanthodon, which has repre- 
sentatives in all the sub-tropical countries of the world, together 
with the South American genera Jdiops and Pseudidiops, and the 
Indian genus Heligmonerus, present a peculiar arrangement of the 
eyes, one pair being situated close together in the middle of the 
front of the caput, while the remaining six form a more or less 
compact group some distance behind them. 
Among the many other genera of the Ctenizinae may be 
mentioned Cyrtauchenius, of which many species inhabit North- 
West Africa, and its close ally Amblyocarenum, represented on both 
shores of the Mediterranean, and in North and South America, 
They differ from Cteniza chiefly in the possession of strong scopulae 
on the tarsi and metatarsi of the first pair of legs, and in the 
double row of teeth with which the tarsal claws are furnished. 
